Ask the groom questions (or make them up) then put them all in a hat and have friends ask her, then if she gets it right give her a pressie (tell everyone before hand to bring along a token present - maybe something old, something new, something borrowed, something blue) and if she's wrong get her to do a dare (get her to get her own "something borrowed" from people in the pub or just give her a rubbish "something old" present)
Bring a little book (or arrange it before hand) that everyone can write in some nice things about the bride or offer pearls of wisdom - then she has a reminder.
Or everyone bring an instrument/ pom-poms/ whatever and pretend to be at a band/ cheerleaders/ whatever conference and just out for a meal but take your role very seriously.
Even if they don't help I wanted to reply to let you know that I feel your pain. I've been bridesmaid a couple of times for brides who didn't want willies and blow up dolls (who wouldn't want that).